Elevator leveling control



Nqv. 5, 1935. v A. J. LIEBENBERG 2,019,917

ELEVATOR LEVELI'N G CONTROL Filed Sept. 14, 1933 s Sheets-Sheet 1 arrowormnuq DEVIL:

INVENTOR Mvl yv ATTORNEYS Nov. '5, 1935. A. J. LIEBENBERG 2,019,917

ELEVATOR LEVELING CONTROL 7 Filed Sept. 14, 1933 3 Sheets-Sheet 3 BYATTORNEYS Patented Nov. 5, 1935 UNITED STATES PATENT OFFICE ELEVATORLEVELING CONTROL Arthur J. Liebenberg,

Cincinnati, Ohio, assignor Application September 14, 1933, Serial No.689,441

6 Claims.

This invention relates to leveling control for electrically operatedelevators.

The invention contemplates the use of a pair of pliotron units, eachunit energized by a stationary vane placed in the elevator hatchway inrelation to a landing or floor level, as primary means of preferred typefor automatically controlling the starting of the elevator motor for aslight movement or travel of the elevator in an appropriate directionafter the general control has functioned to bring the elevator to afloor stop and failed in bringing the elevator floor in level with thelanding. The pliotron units preferably are mounted upon and move withthe elevator, one for up leveling motor starting control and the secondfor down leveling motor starting control, each unit cooperating with arespective vane, one for each floor or landing for a definite startingdirection control governed at which side of the landing the floor of theelevator is out of level, asabove or below, and for the control 01' anelectro-mechanically operated switch actuated by a frictional couplingwith the elevator motor shaft in its leveling starting motion orrotation for cut-out or stopping control of the motor. The levelingsystem or controlling devices can be incorporated with various types ofelectric elevator control systems, either attendant car switch operatedor push button automatic, with the leveling control automatic after thegeneral controlling mechanism has been operated to bring the elevator toa stop, and the car stopping with the elevator floor out of line withthe floor landing.

An object of the invention is to provide a system of leveling controlfor electrically operated elevators, which is entirely automatic andeffective only after the elevator has been brought to a stop by thegeneral controlling devices, and when the floor oi the elevator, whenstopped, is out of line with the landing.

Another object of the invention is to provide an automatic elevatorfloor leveling control easily installed and operated in connection withthe various types of elevator controlling systems, one of simple andcheap construction and in which extremely accurate stops are securedwith lower ratio alternating current motors with less control apparatus.

Various other features and advantages of the invention willbe more fullyset forth in the description of the accompanying drawings, in which:

Figure 1 is a diagram of the leveling control circuits.

Figure 2 is a diagrammatic front view of the motor cut-cut switch forcutting out motor circuit after leveling.

Figure 3 is a diagrammatic side elevation of the same.

Figure 4 is a diagram of the pliotron circuit.

Figure 5 is a front elevation of the motor leveling cut-out switch with,the casing broken away to more completely disclose the mechanism, andillustrating a modified form of construction from that illustrated inFigure 2.

Figure 6 is'a side elevation projected from Figure 5 with parts brokenaway to illustrate the manner in which the switch carrying plates arejournalled.

Figure 7 is a top plan view of the same.

Figure 8 is a view of the device in operation. the magnet having beenenergized, causing the movable plate to swing and contact with the stopon the stationary plate.

The elevator car or cab is equipped with or has installed thereon twopliotron units, one for up direction leveling control and a second fordown direction control. A pair of stationary vanes for each floor orlanding, the vanes of each pair for a landing are suitably spaced apartand relatively offset for respectively cooperating with the pliotronunits, and positioned in the hatchway, one slightly above and the otherslightly below the landing level, causing the unit, when opposlnglyspaced elements of a unit come within intimate relation with the vane,to become energized for a predetermined control of the elevator motorcontrolling mechanism.

In the present instance the pliotron units control a low speed anddirection switch corresponding to the direction in which the car musttravel for floor or landing leveling. Each pliotron unit thereforeautomatically controls the motor controlling switch devices for a motorstarting in one direction, the starting direction depending on whichside of the floor landing level the car has overrun, whereby theelevator motor is started in the appropriate direction for moving thecar from its overrun position to the floor level.

The pliotron units are of duplicate construction and constitute acommercial product in which a pair of air core coils are influenced by aplate passed therebetween. The air core coils are respectively mountedwithin a pair of spaced parallel non-metallic arms extended from theelevator for passing therebetween, a stationary metallic vane mounted inthe hatchway in relation to a landing or station for which the levelingis M governed.

In Figure 4, l indicates a three electrode tube designed for relay workfor use with a standard four pin socket suitably mounted with thefilament of the tube in a vertical position, and the tube under shockabsorbing suspension so that it is not injured by vibration or shock.The tube has a cathode 2 connected to the terminals B and A+ of the unitand the terminal A+ is connected by a conductor 3 to a 3- terminal ofthe second or down level control pliotron unit, connecting the cathodesof the tubes of the two units in series.

The grid 4 of the tube connects with a condenser 5 by a conductor 6 andthe condenser 5 connects with a second condenser I by a conductor 8. Aresistance 9 is placed in shunt with the condenser 5. The condensers 5and 1 connect with a fine wire coil I'll of the transformer by aconductor II and the coil also connects with the terminal A+ by aconductor I2 with the condenser I placed in shunt with the coil Ill. Theopposite or second coil I3 01 the transformer and of coarse wire,connects with the plate ll of the tube by a conductor l5 and with theterminal D+ by a conductor IS.

A third condenser I1 is placed in shunt with the terminals D+ and A+ byconductors l9 and 20.

For the purpose of exemplifying the leveling control and the mechanismemployed, it will be assumed that the elevator controlling deviceseither as a manually actuated switch or automatic push button have beenoperated for bringing the car to a stop at a floor landing, and that thecar has moved either short of the landing level or has overrun the samewithin a leveling zone to render either of a pair of pliotron unitsefi'ective to become energized for operating a relay which in turncontrols a circuit for operating a motor controlling switch as the maindirection or starting switch.

As diagramed in Figure 1, various control devices for motor, low speed,high speed, interlocking, elevator, brake, etc., havebeen eliminated forthe purpose of simplifying the disclosure.

It may also be assumed that the elevator has stopped short of thelanding level and the pliotron unit for the motor up-starting controlenergized due to its relation with a stationary vane in the elevatorhatchway as projected between the spaced coils Ill, l3 oi the uppliotron unit. The terminals B- for the cathode of the tube of the uppliotron unit connects with the electric source of supply of power feedline by a conductor 2|. The electric source for elevator service isusually from a generator of a motor generator unit when the mainelectric power for the elevator motor is an alternating current,although the electric current supply for the control devices may be fromany other available source.

The conductor 2i may include or have interposed therein a switch 22either manually or electrically operated for controlling the circuit tothe pliotron units, the switch preferably being located in the elevatorcab or car for cutting out the automatic leveling control for operationof the car in the general manner.

The pliotron units connect in series respectively with the circuits thatconnect with the elevator motor main direction switches and are onlyeiTective for motor starting in an appropriate direction after theelevator has either overrun or is short of its landing. The up pliotronunit connects in series with the feed line or circuit that connects withthe elevator motor main direction switches and when energized controlsthe circuit to the motor up direction switch as one of the maindirection switches on the elevator motor controlling apparatus.

A conductor 23 connects with the D+ terminal of the up pliotron unit andwith a magnet coil or a switch device or relay designated U--24, therelay 0: switch device having one set of normally open contacts whichare closed when the magnet coil of the switch U-24 is energized for acircuit control to the main up direction switch of the motor and inparticular for a control of the circuit to the magnet coil of the motorup direction switch designated as Ul.

The pliotron units, preferably, may be referred to as electric dischargedevices, each provided with a pair of electric coils ill and i3 in theinput or grid and out-put or plate circuits respectively, which coilsare so mounted as to be in mutual inductive relation with each otheralthough spaced apart somewhat and thereby maintain the dischargedevices in an oscillating condition. Under these conditions the coilsfor the relays U--24 and D-2l are in efiect deenergized, the directioncurrent through the coils being of a low value as compared to thecurrent ,required to operate them. The vanes which are cally isolate thetwo coils of each pair when it comes therebetween, and consequently theoscillating condition in the discharge device is terminated. Under theseconditions a direction current flows in the out-put circuit of theparticular discharge device and energizes the selected relay coil U-24or D-21, as the case may be.

A conductor 26 connects in branch with the magnet coil of the upleveling switch U-24 and also with the magnet coil of a similar switchor relay D-21 for down leveling control, the latter controlled by thesecond or down pliotron unit. The conductor 25 connects with a magnetcoil of a relay 28 and in branch with one of the set of contacts of arelay 29. The relay 29 is a magnetic time relay having two sets ofcontacts. One set of contacts is connected in series with the feed lineto low speed resistance cut-out magnets 01' a pair of relays, as a partof the motor speed control, subsidiary, however, to the directioncontrol of the present system for leveling, while the second set ofcontacts connect in series with the feed line to the magnet coil of arelay 28 and as shown in the diagram, one of the contacts connects witha conductor 3!! to the feed line 3|.

In the circuit or conductor 26, a set of normally closed contacts of amagnetictime relay 32 are interposed. The coilof therelay 32 isenergized through normally open contacts of a relay which has its magnetcoil in series with the car switch circuit, also subsidiary to thepresent system.

The time relay 32 is employed to give the elevator opportunity tostablize before either of the leveling relays U-24 and D2l come intoplay. The relay D2'I has its magnet coil in circuit connection with thedown pliotron unit which is substantially of a construction asheretofore described for the up pliotron unit. The magnet coil of therelay D2l is connected by a conductor 33 with the D+ terminal of thedown pliotron unit and with the conductor 26 which is common to thecoils of both leveling relays U2l and D2l. The timing is minute; merelysufficient to permit the various devices to follow a sequence more orless necessary for eflicient control.

As for example, relay 32 is timed or rather is retarded in its operationso that its contacts are not quickly closed, to allow the motorreversing, either direction switch Ul or D-2, to normalize after a carswitch control, before either again is influenced for a motor startingleveling control by either of the leveling relays U24 or D 25, allowingthe car to stop before it is again started in the appropriate directionfor leveling.

The relay 28 has one set of normally closed and one set of normally opencontacts. The normally closed contacts connect in series with a commonfeed line to the car switch, and not particularly concerned with theleveling control. The normally open contacts connect in series with afeed line 34 through a conductor 35 and with a magnet coil of anelectro-mechanically operated or brake switch device at the end of theelevator motor shaft and thence to the feed line 3|. The coil of therelay 28 connects in series with the contacts of the relays U24 andD--21 and acts as an interlock to the car switch circuit when the car isleveling so that as long as the relay 2!! is energized, the movement ofthe car switch is inefiective.

Also, when the relay 29 is energized, it causes the magnet coil 36 ofthe brake switch to be energized resulting in a set of normally closedcontacts of said brake switch device to be broken with the rotation ofthe motor, thereby breaking the circuit to the magnet coil of the relay29. The coil of the magnetic time relay 31 connects with the feed line3| by a conductor 38 having a resistance 40 interposed therein and by aconductor 4| with the conductor 35 to a contact of the normally opencontacts of the relay 28.

The coil of the relay 28 connects in series with the contacts of therelays U-24 and D-21 serving for both up and down leveling control, byconductors 42 and 43. Each of the relays U-24 and D21 has one set ofnormally open !contacts. The contacts for the relay U 24 when closedconnect in series with the coil of the elevator motor up directionswitch UI by a conductor 44 and the contacts for the relay D21 with themotor down direction switch D-2 by a conductor 46.

The coils of both main direction switches U-land D-2 are connected by aconductor 41 with the feed line 34. Contacts of various other controlrelays may be interposed in the circuit connecting the contacts of therelays U24 and 13-21 with the motor direction switches Ul and D2 as forinterlock control to prevent the direction switches from beingsimultaneously operated.

The pliotron units control the starting of the motor in appropriatedirection for leveling after the car has been brought substantially to astop in either an overrun or short position relative to the landing andan electro-mechanically operated or brake switch on or in connectionwith the motor shaft controls the stopping of the motor for leveling.

The electro-mechanically operated or brake switch on or in connectionwith the motor shaft comprises a pair of relatively opposing brakelevers 49-49, arranged at opposite sides of a drum or pulley 50 fixed onan end of the shaft 5| of the elevator motor.

The brake levers, each at its upper end, are

pivotally mounted on a swinging plate 52. The brake levers are eachprovided with a shoe 53 for frictionally contacting with the peripheryof the pulley, when the levers are compressed toward each other by themagnet 36. The levers are held in a retracted position to release orfree the shoes from the pulley by a spring 54 engaged about a rod 55connecting the upper ends of the levers 49. The lever supporting plate52 is pivoted to a stationary bracket or support 55a with the fulcrumaxis coaxial with the axis of the motor shaft. Thus, when the brakelevers are clamped to the pulley the rotation of the motor shaft ineither direction will swing the plate 52 in a direction corresponding tothe direction of shaft rotation. The magnet 36 when energized attractsthe brake levers compressing the shoes thereof against a pulleyfrictionally connecting the levers and plate 52 with the motor shaft.The lower end of the plate 52 carries an insulated stud 56 extendinglaterally from the plate and between a pair of relatively opposingyieldable stationary contacts 5151 which, when both are in connectionwith the stud, are in circuit connection with the coil of the relay 29and this circuit is broken with the starting of the motor, swinging theplate 52 through its clutch connection with the motor shaft by the brakelevers 49 in frictional or gripping contact with the pulley 50.

The contacts 5151 when contacting or enaged with the stud 56, connectwith the feed line 34 by a conductor 58, and by a conductor 59 with themagnet coil of the relay 29, and from the coil of the relay 29 to thefeed line 3|, the conductor 59 having a resistance element 60 interposedtherein.

The brake switch serves to break the motor circuit or circuit for eitherof the direction switches, whichever is in service for motor starting,and therefore fimctions only for stopping the motor after it has beenstarted by either of the pliotron units, or other circuit controllingmeans influenced or actuated by the elevator cab at either a short orover-run position relative to a floor or landing or by the elevator cabwhen within a leveling zone.

The contacts 5151 are normally closed and only broken after the motorhas been started for leveling. Therefore the coil of the relay 29 in thecircuit with the contacts 5151 is energized continuously. As thecontacts 5151 are broken quickly, it is necessary to use an adjustablerelay in series with the magnet coil of the relay 28 which is in serieswith the contacts of the relay U-24 and D 21 controlling the circuit tothe main direction switches U--i and D-2 respectively for otherwise theleveling would be accomplished too slowly. The relay 29, therefore is atime relay adjustable so that the speed of leveling can be increased ordecreased.

The contacts of the relay 29 control the cir cuit from the feed line 3|tothe pliotron units and also the circuit from the feed line 3| to thecontacts of the relays U-24 and D21 and motor direction switches U! andD'I when the contacts of the relays U--24 and D-21 are closed. Theremust be a suflicient time allowance to accomplish the full levelingmovement of the elevator, and for a continuous and sequencialperformance of the leveling devices of the system, and avoid any repeatperformance which may result from too quick operation of some of thedevices.

Several of the relays which have been designated as time relays are of atype in which the armature thereof is retarded or sluggish in its activemovement upon being influenced by its magnet coil to permit other relaysto normalize before a control circuit is completed. The structure ofsuchtypes of relays and their use are common in the art.

The pliotron units are ineffective to exert any influence over the motorduring travel of the car under control of the car switch, due to theoperation of the interlock relay 32, as its contacts are in the feedcircuit to the leveling relays U24 and D2'l, which are open while themain controlling mechanism to the motor is in operation and the feedcircuit for the leveling relays does not close until the elevator comesto a stop. As the leveling mechanism is auxiliary to the main motorcontrol mechanism it can be cut out at will and the elevator operated inthe general manner.

An operation of the leveling system is as follows: After the elevatorhas come to a stop or point at which the general controlling mechanismfor a landing stop should not bring the elevator to the landing level,say short of the landing, a stationary vane in the hatchway for thelanding will extend between the coils I0, l3 oi the up pliotron unit onthe elevator energizing relay U24, if the lock-out relay 32 of the motorcontrolled system is de-energized. The pliotron unit will cause theleveling relay U24 to be energized, closing its contacts and completingthe circuit for the main up direction switch Ul of the motor controller,starting the motor in an up direction. The circuit extends from the uppliotron unit by a conductor 22 to the magnet coil of the up levelingrelay U-24, through the coil of saidrelay, and by a conductor 26 to aset of contacts of the relay 29, which are closed as the coil of saidrelay is normally constantly energized, and thence by a conductor 30 tothe feed line 3|, Energizing the coil of the relay. U24 also completes acircuit from the feed line 3|, conductor 30, closed contacts of theenergized relay 29, thence through the coil of relay 28, and conductors42, 44, which are connected through the closing of the contactscontrolled by relay U-24 to the motor main up direction controllingswitch U-I. The relay 28 having its magnet coil in circuit with thedirection switch Ul is likewise energized closing its contacts,completing the circuit to the magnet 36 of the brake switch at the endof the motor shaft, compressing the brake levers 49-49, coupling theswinging plate 52 to the motor shaft, the plate thereby moving with themotor shaft breaking the contacts 51-51 and the circuit to the timerelay 29 which in turn completes the controlling circuit to the updirection switch U-l.

When the car switch has been thrown to its neutral position forcontrolling the motor for a car stop at a selected floor, should the carfail to stop at the floor level and be in a position below the level ofthe floor, relay 32 will be deenergized, being thrown in circuitconnection upon placing the car lever to neutral position. The upelectron unit will energize the up relay U24, closing the controllingcircuit to the up direction switch U-I a controlling circuit for thedirection switch Ul being complete from the feed line 3|, conductor 30,contacts of relay 29, conductor 26, through coil of relay 28, conductor42, to contacts of relay U-24, conductor 44, to the coil of directionswitch Ul, and thence by conductor 41 with the feed line 34. Acontrolling circuit, likewise, will be completed with the magnet coil 36of the brake switch, connecting with the feed line 3| through conductor35, and by a conductor 35 through the contacts of relay 28, connectingwith the feed line 34 through the conductor 35. The coil of the relay 28is energized simultaneously with the energization of either coils U-24or D- 21, being connected in the circuit of the coils of said relay U-24and D2I by a conductor 26, contacts of relay 32, and by conductor 42with the contacts of either of said relays U-24 and D-2'|, and the relaycoils of the direction switches in U| and D2, and by conductor 41 withthe feed line 34, thereby controlling the engagement of the clutch withthe motor shaft for operation with the rotation of the shaft to open themotor circuit controlling switch in the running circuit 15 of the motor.

As the leveling motion required is usually slight, say within one inchof the floor landing, only a fraction of a revolution of the motor isnecessary. The motor starting at slow speed, 20

will, however, respond sufficiently to function within time allowancesmade and without a jerk.

On alternating current motors different amounts of starting resistanceare necessary for different loadings if smooth starting is de- 25 sired.Also, static friction requires different torques for different loads,and it is necessary to restrain the excess torque needed to overcomestatic friction as quickly as possible, as soon as the machine starts tomove. quire no consideration due to the fact that for leveling, themotor starts at low speed requiring no speed regulation, and the motorcircuit is cut out as quickly as possible after motor starting,

the motor moving but a slight fraction of a 35 revolution, as a smalldistance of car travel is only required for leveling.

The pliotron units are preferably employed as a medium responsive whenthe car in its traverse, reaches or passes definite points or moveswithin zones without making any contacting or tripping connectionbetween the relative stationary and moving parts, thereby eliminatingwear and breakage of the parts.

It is obvious, however, that mechanical types of circuit control orelectric current make and break devices may be employed, trip actuatedby the moving car at certain points in its traverse for operating theswitch device actuated by the motor for cutting off the motor current,after a starting for leveling through its starting momentum effectingits own stopping control,

Referring to Figures 5 to 8 inclusive, illustrating a modified form ofmotor operated switch for cutting out motor circuit for car leveling,the construction of switch provides for an increased motor levelingoperating interval, or increased arc of motor shaft rotation beforecircuit to elevator motor is cut off. This facilitates in theinstallation and in regulation.

In the modification the opposed contacts 51, 51 are mounted as a unitfor a slight arc of movement with the movable contact or stud 55. A pairof brake levers 49, 49 are pivotally mounted, each respectively upon astud 6| fixed to and laterally extending from a swinging plate 52. Thebrake levers are arranged to clasp about opposite sides of the end ofthe elevator motor shaft 5|, or pulley fixed thereon, and adapted to becompressed against the periphery of the motor shaft by a magnet 36mounted upon the rear side of the swinging plate 52 between the opposingends or arms of the brake levers 49.

The brake levers are neutralized or retracted, each by a spring 62 onone end of a rod 63 lcose- 1 Such factors re- 30 ly extending across theupper ends of the brake levers 49.

The swinging plate 52 is journalled upon a stud bolt 64 mounted upon andengaged through a cross bar 64 rigidly secured upon brackets 65, 65fixed to the interior of the casingv 66. The lower or depending end ofthe swinging plate 52 carries a laterally extended stud 56, as a movablecontact extending between the movable contacts 51, 51, upon a secondswinging plate 61. This second swinging plate 61 is pivoted upon thestud bolt 64 and depends therefrom parallel with the swinging plate 52.The movable contacts 51, each is mounted within a tubular housing 68,fixed to the lower end of the swinging plate 61 and urged outwardlytoward and against the stud 56 by a spring 69, enclosed and confinedwithin the housing 68 and bearing against the head end of the contact51.

A rigid plate 10 is fixed to and depends from the cross bar 64, itslower end provided with a laterally extended stop lug 1|, to bealternately engaged by a pair of lugs 12 projecting from the secondswinging plate 61 at relatively opposite sides of the stationary stoplug 1 I. The swinging plate 61 is provided with a plurality of apertures13 for adjustably locating the lugs 12.

In a neutral position of the parts as shown in Figure the swingingplates 52 and 61 are in a perpendicular position, and the contacts 51,51 engaged with the contact stud 56. Upon starting the elevator motor ineither forward or reverse direction of rotation depending upon thedirection required for car fioor leveling, the magnet 36 appropriatelywith the motor starting is energized actuating the brake levers 49, 49for clutching to the motor shaft. The swinging plates 52, 61 swing as aunit with the rotation of the motor shaft until the stationary stop lug1| is engaged by either one of the lugs 12 of the swinging plate 61arresting the same and the continued movement of the swinging plate 52compresses on the movable contacts 51 breaking contact with the othermovable contact 51, opening a control circuit to the motor for motorstopping.

It is recognized that the system provides for motor leveling control ineither forward or reverse directions of motor rotation, to accommodatefor elevator either coming short or overrunning a landing, and for someinstallations the leveling control may be only in one direction as whenthe elevator only services the floors in one direction, in whichinstance the control system for leveling need only be equipped for a onedirection control.

Having described my invention, I claim:

1. An automatic leveling control for an electric motor driven elevatorcomprising, a pair of electro-magnetically operated direction motorcontrolling switches, one for up and the other for down motor directioncontrol, a pair of pliotron units moving with the elevator, one formotor up direction leveling control and the second for motor downdirection leveling control, vanes mounted in the elevator hatchway withrespect to a floor level, each respectively to cooperate with a pliotronunit, relays respectively controlled by said pliotron units, each incircuit with one of the pliotron units and effective therewith forcontrolling the circuit to one of said motor direction switches, for amotor starting control when a pliotron unit is in cooperation with avane, and an electro-magnetically operated switch device responsive witheither of said relays for frictionally coupling with the motor shaftwhen the motor has started in a car floor leveling movement for cuttingout the circuit to said motor direction controlling switches to effectthe stop of the car when level with the floor.

2. An automatic leveling control for an electric 5 units moving with theelevator, one for motor up direction leveling control and the second formotor down direction leveling control, vanes mounted in the elevatorhatchway with respect to a floor level, each respectively to cooperatewith a pliotron unit, for respectively controlling said 15 motorcontrolling switches, for a motor starting control when a pliotron unitis in cooperation with a vane, and an electro-magnetically operatedswitch device responsive with either of said motor controlling switchesfor frictionally coupling with the motor shaft when the motor hasstarted in a car leveling movement for cutting out the circuit to saidmotor direction controlling switches to effect the stop of the car whenlevel with the floor. 3. An automatic leveling control for an electricmotor driven elevator comprising, a pair of electro-magneticallyoperated direction motor controlling switches, one for up and the otherfor down motor direction control, a pair of pliotron units moving withthe elevator, one for motor up direction leveling control and the secondfor motor down direction leveling control, vanes mounted in the elevatorhatchway with respect to a floor level, each respectively for operatinga motor direction controlling switch for controlling an operatingcircuit to one of said motor direction switches for a motor startingcontrol when a pliotron unit is in cooperation with a vane, a

switch in a controlling circuit of said motor di- 4 rection controllingswitches, and means for operating the switch including a clutchirictionally coupling to the motor shaft when the motor has started in acar leveling movement for cutting out the control circuit to said motordirection controlling switches to effect the stop of the car when levelwith the floor.

4. An automatic leveling control for an electric motor driven elevatorcomprising, a pair of electro-magn'etically operated direction motorcontrolling switches, one for up and the other for down motor directioncontrol, a pair of pliotron units moving with the elevator, one formotor up direction leveling control and the second for motor downdirection leveling control, vanes mounted in the elevator hatchway withrespect to a floor level each respectively to cooperate with a pliotronunit controlling the circuit of a pliotron unit, and one of said motordirection switches, for a motor starting when a pliotron unit is incooperation with the vane, a switch in the running circuit of the motor,and means responsive with the control of either of said motor directionswitches for operatively connecting the switch with the motor to causeopening of the 5 switch to effect the stop of the car when level withthe floor.

5. In an electric elevator, the combination of a hatchway, a car in saidhatchway, an electric motor for driving the car, reversing switches forcontrolling said motor for forward and reverse operation,leveling meansfor governing the motion of said motor and leveling the travel of saidcar, comprising a pair of devices mounted in said hatchway in spacedrelation with each other and in relation to a floor Ievei at which thecar control is to be effective, a pair of devices mounted on said cararranged each to cooperate respectively with one of said first pair ofdevices for rendering said reversing switches selectively responsive formotor control and direction of movement of said car, a switch device inthe running circuit of the motor, and means for operating said switchresponsive with said reversing switches and including a clutch forengaging the motor shaft to cause opening of the switch to efiect thestop of the motor when the car is level with the floor.

6. In a. floor leveling control for electric motor driven elevators forstopping an elevator level with a floor, comprising a switch in therunning circuit of the motor and means for operating the switch,including a clutch for engaging the motor shaft and positionedresponsive means efiective to control engagement of the clutch inaccordance with the position of the car with respect to the floors, tocause opening of the switch to effect the stop of the car when levelwith the floor.

ARTHUR J. LIEBENBERG.

